A real-time location system can be used for tracking containers in modern marine terminals, tracking vehicles at rental car agencies and similar venues, tracking inventory in a warehouse or tracking other assets. Examples of such real-time location systems and methods are disclosed in commonly assigned U.S. Pat. Nos. 5,920,287; 5,995,046; 6,121,926; 6,127,976; 6,657,586; 6,812,839; and U.S. Published Patent Application Nos. 2002/0181565 and 2006/0220851, the disclosures which are hereby incorporated by reference in their entirety.
In one type of location system, for example, at a marine terminal or rental car agency, challenges are presented because of the many sources of information. For example, telemetry location could come from the location system. Other information could come from external events, e.g., a customer, including messages. From these disparate sources of information, it is desirable to determine what events occur at the marine terminal or other venue. It is desirable to have these different windows into events, especially when information is inconsistent. As information is added, it becomes increasingly difficult to construct the logic to determine an asset location. Previous systems typically used numerous if-else logic statements in code. As information was received, it was difficult to determine how to incorporate the additional information into an algorithm.
If-else rules are typically conditional statements and complicated. If-else rules define operations to be carried out if none of any specifically described conditions occur. There could be many different actions to be performed depending on the result of tests or data that has been received, making complicated if-else logic statements. This type of system and code can become complicated.
It would be more desirable if a rule or “squaring” approach could be used because of the complexity involved in these location systems. For example, in a marine terminal, there are cranes that pick containers off a ship and drop them into a truck or onto a railcar. It is desirable to determine what truck or railcar the cargo container was positioned. The location system by itself could be accurate to a foot and that would be enough to determine which truck a cargo container was positioned. Unfortunately, the location system is not always accurate because of different factors whether environmental or technical. There may be several trucks within a certain radius and it is desirable if the system could narrow down on which one of the trucks the container had been placed. There could also be telemetry from the trucks. For example, sensor data could be admitted, telling the system that a container was detected such as by an ultrasonic sensor on a container or loader. These different sources of information are a challenge. Also, a sensor could break, making the if-else rules difficult. The data could also be inconsistent. Other sensors such as a moving/not-moving sensor could be broken on a utility tractor rig (UTR), which may have been stopped. Because the sensor was not working, the UTR would appear to be moving, for example. It would be desirable if a real-time location system could be implemented that would not rule out certain factors for consideration because a UTR was considered to be moving. For this reason, a weighted rule system is desirable, which could be increasingly important in a complicated modern marine terminal, rail terminal, or rental car venue.
For example, the modern marine terminal must efficiently process an increasing number of containers in an area of limited space with little, if any, land available for expansion. Capacity demands are increasing rapidly with higher volumes of container traffic worldwide and new, larger container ships coming on-line. Specific containers should be located on demand among the thousands of containers at any given time, but this can be difficult if there is a lack of an accurate and real-time container identification and tracking system of drayage tractors, switched tractors, wheeled container chassis, top and side pick loaders, and gantry and quay cranes. Locating a container can also be complicated by the number of ways in which containers can be processed through a terminal. For example, some containers arrive via a vessel or train and are driven through a check-in gate by an outside truck. Once a container enters the terminal, it can be parked on a chassis or cart in a terminal, or removed from the chassis and placed on top a stack of shipping containers. When a container is to be retrieved, it must be located among the thousands of containers in the terminal. These containers may be moved around the terminal by outside drivers, or moved by marine terminal drivers, using a client's tractor with terminal equipment.
Maintaining inventory and track of every container in the terminal is difficult and the large number of containers and the different ways in which the containers can be moved throughout the terminal makes it difficult to locate a specific container when it is needed. Also, the marine terminal often does not run smoothly and this complicates the location system.
Different systems are used for processing containers through a marine terminal, such as discharging a container from a vessel to chassis. For example, containers may arrive in a marine terminal via a vessel or rail. Other containers can be discharged from a vessel to ground. When containers arrive at a marine terminal via a vessel or train, they can be “discharged” or placed on a cart to be stacked, instead of parked on a chassis. Other containers can be checked in at a gate. Instead of arriving via a vessel or train, a container may arrive via a central check-in gate. Drivers employed by customers of the marine terminal arrive at the gate for check-in, where they pass through a gate much like a highway toll plaza. At this gate, information is collected about the container, after which the driver is instructed either to park the chassis and container in a particular location or to discharge the container to ground.
These different systems for processing containers make it difficult to track the containers in a marine terminal. Tracking container movement throughout the marine terminal is important because searching for any misplaced containers requires time and labor costs and adds to the shipping time of goods.